Make drawing methods visible to subclasses

Update README.md

Downgrade gradle plugin

Add notice

Update version name

Fix Rosemoe#69 - Finish composing text state when composing text is s…

…et to be empty

Improve drawing speed

Improve CachedIndexer's cache finding
Improve speed of Cursor#isSelected
Fix layout of sample app

- Rise SDK Requirement for all modules

Move ContentActions into UndoManager

Fix bug that select action mode will not exit after input method exit select mode
Reformat CodeEditor.java

Fix bug in selecting text using WordwrapLayout

Migrate to Java 8
Migrate to Android R in crash log saving
Fix typos of some files